Qml: Don't crash when as-casting to type with errors

Such types don't have a compilation unit, but we still know their names.

Fixes: QTBUG-98792
Change-Id: I2db8dea3a5a02ec1492f7f7a054fd3ad4c6ad69a
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>
(cherry picked from commit e0cd201e91ae64b9c03e0128cd17656b00611fbb)

4 files changed, 35 insertions, 2 deletions

diff --git a/src/qml/qml/qqmltypewrapper.cpp b/src/qml/qml/qqmltypewrapper.cpp
index 6bf9455e17..00c28f90c7 100644
--- a/src/qml/qml/qqmltypewrapper.cpp
+++ b/src/qml/qml/qqmltypewrapper.cpp
@@ -419,8 +419,10 @@ ReturnedValue QQmlTypeWrapper::virtualInstanceOf(const Object *typeObject, const
             return Encode(false);
 
         QQmlRefPointer<QQmlTypeData> td = qenginepriv->typeLoader.getType(typeWrapper->d()->type().sourceUrl());
-        ExecutableCompilationUnit *cu = td->compilationUnit();
-        myQmlType = qenginepriv->metaObjectForType(cu->metaTypeId);
+        if (ExecutableCompilationUnit *cu = td->compilationUnit())
+            myQmlType = qenginepriv->metaObjectForType(cu->metaTypeId);
+        else
+            return Encode(false); // It seems myQmlType has some errors, so we could not compile it.
     } else {
         myQmlType = qenginepriv->metaObjectForType(myTypeId);
     }
diff --git a/tests/auto/qml/qqmllanguage/data/Broken.qml b/tests/auto/qml/qqmllanguage/data/Broken.qml
new file mode 100644
index 0000000000..e1b61f31f4
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/Broken.qml
@@ -0,0 +1,5 @@
+import QtQml
+
+QtObject {
+    notThere: 5
+}
diff --git a/tests/auto/qml/qqmllanguage/data/asBroken.qml b/tests/auto/qml/qqmllanguage/data/asBroken.qml
new file mode 100644
index 0000000000..bd88d14c76
--- /dev/null
+++ b/tests/auto/qml/qqmllanguage/data/asBroken.qml
@@ -0,0 +1,6 @@
+import QtQml 2.15
+
+QtObject {
+    id: self
+    property var selfAsBroken: self as Broken
+}
diff --git a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
index ac6634290a..92d0069ce4 100644
--- a/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
+++ b/tests/auto/qml/qqmllanguage/tst_qqmllanguage.cpp
@@ -343,6 +343,8 @@ private slots:
     void bindingAliasToComponentUrl();
     void badGroupedProperty();
 
+    void objectAsBroken();
+
 private:
     QQmlEngine engine;
     QStringList defaultImportPathList;
@@ -5951,6 +5953,24 @@ void tst_qqmllanguage::badGroupedProperty()
              .arg(url.toString()));
 }
 
+void tst_qqmllanguage::objectAsBroken()
+{
+    QQmlEngine engine;
+    QQmlComponent c(&engine, testFileUrl("asBroken.qml"));
+    QVERIFY2(c.isReady(), qPrintable(c.errorString()));
+    QScopedPointer<QObject> o(c.create());
+    QVERIFY(!o.isNull());
+    QVariant selfAsBroken = o->property("selfAsBroken");
+    QVERIFY(selfAsBroken.isValid());
+
+    // 5.15 doesn't enforce type annotation. So the "as" cast succeeds even though
+    // the target type cannot be resolved.
+    QCOMPARE(selfAsBroken.value<QObject *>(), o.data());
+
+    QQmlComponent b(&engine, testFileUrl("Broken.qml"));
+    QVERIFY(b.isError());
+}
+
 QTEST_MAIN(tst_qqmllanguage)
 
 #include "tst_qqmllanguage.moc"